Releasable lock for loaded member



Aug. 16, 1966 J. A. HARPER 3,266,340

RELEASABLE LOCK'FOR LOADED MEMBER Filed June 11, 1964 2 Sheets-Sheetv l J; ,4. Aer air J W ##orw 19% .r

Aug. 16, 1966 J. A. HARPER 3,256,340

RELEASABLE LOOK FOR LOADED MEMBER Filed June 11, 1964 2 Sheets-Sheet 2 65/5 7 za 40 v 1% United States Patent 3,266,340 RELEASABLE LOCK FOR LOADED MEMBER Jay A. Harper, Gardena, Calif., assignor to Acme Machine Works, Inc., Hawthorne, Calif, a corporation of California Filed June 11, 1964, Ser. No. 374,437 16 Claims. (Cl. 74-584) This invention relates to a latch mechanism, and more specifically, relates to a positively acting mechanism for locking a member in opposition to a load of relatively high magnitude and for quickly releasing the loaded member in response to a release force of exceedingly small magnitude.

For the purpose of disclosure, the invention is described herein as embodied in a latch mechanism for immobilizing a rod in opposition to a longitudinal load exerted on the rod by a heavy spring. This selected embodiment of the invention will provide ample guidance for those skilled in the art who may have occasion to apply the invention to other specific purposes including situations where the load is created by means other than spring means.

There are many instances where it is desirable to provide an easily releasable latch or lock to withstand a relatively heavy load. In some instances, for example, it is desirable to store energy in a spring to be released when required to exert sudden thrust or pull for some useful purpose. The energy may be released, for example, to create an emergency control force or to displace some object.

The basic problem involved in providing an easily releasable latch capable of resisting a load of large magnitude may be appreciated from considering a simple conventional arrangement wherein a latch member is retractable transversely of a longitudinally loaded rod and the latch member has a shoulder engaging a cooperating shoulder of the rod with the co-acting surfaces of the two shoulders perpendicular to the direction of the load force. It is usually desirable to minimize the area of the rod shoulder with the result that the unit load on the cooperating surfaces becomes excessive. Consequently a relatively large release force is required to retract the latch member under the heavy pressure exerted by the load. A second consequence is that the employment of co-acting shoulders that are vperpendicular to the direction of the load results in heavy wear of the shoulders and a troublesome tendency for the edges of the shoulers to chip.

A further problem arises because at least two latch members should be provided to engage opposite sides of the rod for balanced resistance to the load. Close synchronism of the two latch members is required for release of the loaded rod in a balanced manner.

These difiiculties may be largely avoided by employing two diametrically opposite latch members to provide two pairs of co-acting shoulders and by inclining the two pairs of cO-tctingshOulders so that the load tends to cam the two latch m embers synchronously out of their released positions with minimum wear and minimum tendency to damage the co-acting shoulders. A new difiiculty arises,

however, because such an arrangement by virtue of its cam action tends to be self-releasing and therefore inherently unsafe. The present invention solves the problem of making such a desirable arrangement safe and reliable.

The invention provides at least two pairs of cam surfaces acting in series on each side of the loaded rod. Thus on each of the two diametrically opposite sides of the rod, an inclined shoulder of the rod tends to cam a corresponding latch member to release position in opposition to a corresponding blocking member and, in turn, the latch member tends to earn the blocking member to released position. Each of the two blocking members is normally retained in its effective position by a correspond- 3,265,346 Patented August 16, 1966 ing pair of toggle links which tend to collapse by knee action in response to the cam action on the blocking member. Finally, what may be termed a locking member, is normally at an effective locking position to prevent collapse of two pairs of toggle links, the locking member being retractable from its normal position to release the toggle links.

The arrangement is such that the knee action of the two pairs of toggle links is directed perpendicularly against longitudinal surfaces of the locking member to avoid any tendency for the applied forces to cam the locking member towards its release position. Retraction of the locking member longitudinally from its retracted position permits the two pairs of toggle links to collapse in response to the reaction of the load on the latch member, the reaction being transmitted by cam action from the latch member to the two pairs of toggle links.

In the preferred practice of the invention there are three reasons to account for the fact that only a slight release force is required for retraction of the locking member. One reason, of course, is that the reaction of the load force is directed to a longitudinal surface of the locking member perpendicular thereto so that the resistance to the retraction of the locking member by a load force is a simple frictional resistance. A second and more important reason is that only a small residual portion of the reaction to the load force actually reaches the longitudinal surface of the locking member.

With reference to the second reason, the invention provides for a series of reductions of the reaction force before the reaction force is applied to the longitudinal surface of the locking member, each reduction in the reaction force involving the creation of two divergent component forces. Thus at each region of engagement of each latch member with the loaded member, two divergent components of reaction force are created, one of the two being a radial component that tends to retract the latch member. In the same manner, two divergent components of the reduced reaction force are created at the region of contact of each latch member with the corresponding blocking member, one of the two components being an axial component tending to retract the blocking member from its eifective position. Finally two diverging components of the twice reduced reaction force are created by each pair of toggle links, one of the two residual components being a minor radially inward component applied to the cooperating locking member. Thus the reaction to the load force is divided three times consecutively before the reaction reaches the control Zone at the surface of the locking member.

The [third reason for the low magnitude of the release force is that when the locking member is retracted over only a small fraction of the range of release movement, a reverse cam action is triggered that uses the reaction to the load to complete the release movement. This reverse ca m action which utilizes a normally inoperative cam surface on the locking member also has the advantage of speeding up the release action to make the release action nearly instantaneous.

The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely ill strative:

FIG. 1 is a longitudinal View largely in section and partly in side elevation illustrating the selected embodimerit of the invention, the figure showing how two longitudinal blocking arms cooperate with two corresponding latch members;

FIG. 2 is a longitudinal section along the line 22 of FIG. 1, the view showing the two pairs of toggle links that control the two blocking arms;

effect two radial sections 90 apart;

FIG. 5 is a similar view showing the locking member fully retracted for release of the two latch members; and

FIG. 6 is a diametrical sectional view showing how the manually retractable locking member exents cam force on the two pairs of toggle links when the locking member is manually released after it is retracted.

General arrangement In the drawings illustrating the selected embodiment of the invention, a rod, generally designated 10 is telescoped at one end into a structure including a cylinder 12 capable of withstanding the contemplated heavy longitudinal load on the rod, In this instance, the load is exerted by a relatively heavy coil spring 14 inside the cylinder acting under compression against a collar 15 on the inner end of the rod.

The overall assembly comprising the rod 10 and the cylinder 12 may be either expanded or contracted by the action of the spring and either the rod or the cylinder may be anchored with the other free to release the energy stored by the spring. In the construction shown, the spring force is exerted against the face of the collar 15 in the direction to contract the assembly and it is contemplated that the cylinder 12 will be anchored to cause the rod to exert a pulling force for some useful purpose. Obviously, the coil spring 14 may be transposed to exert pressure against the opposite sides of the collar 15 to cause the rod 10 to exert thrust instead of pulling force.

In the construction shown, the rod 10 is provided with an eye fitting 16 for connection to a movable object and the rod incorporates a turnbuckle 18 for adjustment of the overall length of the assemblyv At the opposite end of the assembly, the cylinder 12 fixedly embraces a bushing 20 into which an end rod 22 is adjustably threaded and is releasably secured by a jam nut 24. The end rod 22 is of the so-called self-aligning type incorporating a rotatable ball element 25 with a diametrical bore 26 therein by means of which th cylinder may be anchored to a fixed support.

A selected longitudinal portion of the rod 10 is adapted for engagement by latch means and for this purpose the rod may be formed with a series of circumferential grooves 28 forming circumferential ribs 30 which may be engaged selectively to immobilize the rod in opposition to the longitudinal load imposed by the spring 14. Each of the circumferential grooves 28 is tapered in depth with the consequence that each rib 30 forms an inclined circumferential latching shoulder 32.

The principal working parts of the device include the following: latch means in the form of a pair of diametrically opposite radially retractable latch jaws 34 adapted to enter the circumferential grooves 28 of the rod 10 selectively to engage the corresponding latching shoulders 32; blocking means in the form of a pair of diametrically opposite longitudinal blocking fingers 35 which are unitary with a floating ring 36, the blocking fingers nonmally blocking radial outwand release movement of the two latch jaws 34 and being longitudinally retractable to release the corresponding latch jaws; two diametrically opposite toggle means each comprising two toggle links 38 and 40 whiehnor-mally immobilize the floating ring 36 against release movement of the blocking fingers 35, the two pairs of toggle links being adapted to collapse with radially inward knee action to permit shift of the floating ring and thereby permit release movement of the blocking fingers; a tubular locking member 42 surrounding the rod 10 with ample clearance and normally preventing collapse of the two pairs of toggle links, the locking member being axially retractable to release the toggle links; and a small coil spring 44 loosely surrounding the rod 10 and acting in compression to urge the locking member 42 to its normal effective position.

In the contemplated mode of operation, the longitudinal load which is indicated by the arrow 45 in FIG. 1 tends to cam the two latch jaws 34 radially outward against the two corresponding blocking fingers 35; the consequent radially outward thrust of the two latch jaws 34 tends to cam the two corresponding blocking fingers longtiudinally to their release positions thereby placing the locking fingers under longitudinal tension; the longitudinal force exerted by the two locking fingers on the floating ring 36 tends to collapse the two pairs of toggle links radially inward against the locking member 42, the radially inward force exerted by the two pairs of toggle links being against a cylindrical longitudinal surface 46 (FIG. 2) of the locking member in a direction perpendicular to the surface.

Adjacent the cylindrical surface 46, the locking member I 42 is cut away to form a neck 48 of reduced diameter and a conical cam surface 50 that leads from the neck to the cylindrical surface. When the locking member is shifted axially against the resistance of the small spring 44, the two pairs of toggle links are permitted to collapse radially inwardly to release the floating ring 36 thereby to release the blocking fingers 35 for retraction by cam action on the part of the two latch jaws 34. Thus once the release action is initiated the rod 10 is released by a chain of successive actions in reaction to the load force.

Structural details What may be termed fixed structure for withstanding the load force includes not only the cylinder 12 but also three rings 51, 52 and 53 which are packed together face to face and are united with the cylinder 12, for example, by radial pins (not shown). The middle ring 52 which has a thin cylindrical wall serves as a spacer between the other two rings 51 and 53 to form therewith an annular space for radial guidance of the two latch jaws 34, the spacer ring insuring clearance for free movement of the latch jaws. The two blocking fingers 35 extend into the three rings 51-53, the ring 51 having a pair of diametrically opposite apertures 54 and the ring 53 having a second pair of diametrically opposite apertures 55 aligned therewith to serve as guideways for the two blocking fingers.

Each latch jaw 34 has an inner arcuate latch projection dimensioned to seat selectively in the circumferential grooves 38 of the rod 10, the latch projection being tapered to conform with the cross sectional configuration of the grooves and thus providing an inclined latch shoulder 62 to mate selectively with the inclined latch shoulders 32 of the loaded rod 10. As indicated in FIG. 3, the two latch jaws 34 are continuously urged apart by a pair of concealed coil springs 64 and the two jaws are formed with radial notches 65 to slidingly receive the two blocking fingers 35.

The bottoms or inner radial walls of the radial notches 65 are inclined or tapered'as shown in FIG. 1 to form cam surfaces for cooperation with the blocking fingers 35, the cam surfaces being preferably conically curve-d. Each of the blocking fingers 35 is formed with an end enlargement having an inner inclined cam surface 72 which slidingly cooperates with the corresponding cam surface of the two lat-ch jaws.

The previously mentioned floating ring 36 is connected to the fixed structure by the previously mentioned pairs of toggle links 38, 40. As shown in FIG. 2 each toggle link 38 extends into a corresponding peripheral slot 74 in the floating ring 36 and is pivotally connected to the floating ring by a cross pin 75. In like manner each of the longer toggle links extends into a corresponding peripheral slot 76 of the fixed ring 51 and is pivotally connected to the fixed ring by a cross pin 78.

The two links 38 and 40 of each pair of toggle links are pivotally interconnected by a cross pin 80 and it is to be noted in FIG. 2 that each cross pin 80 is offset radially inwardly from the two cross pins 75 and 78 with the consequence that the cross pins 80 are off center the toggle links to be biased radially inwardly. Thus placing the two pairs of toggle links under longitudinal compression tends to cause the two toggle links to col lapse inwardly with knee action against the locking member 42. It is also to be noted that the inner ends of the toggle links 38 are formed with integral radial projections 82 which are shaped to function as cam followers for cooperation with the previously mentioned conical surface of the locking member 42.

The locking member 42 is formed with a circular operating head 84 which slidingly engages the inner circumferential surface of the cylinder for guidance thereby. The operating head 84 may be manually depressed for release movement of the locking member 42, but in this instance it is contemplated that the locking member will be released by remote control. For this purpose a solenoid 85 may be mounted on the end of the cylinder 12 by a plurality of circumferentially spaced bracket arms 86 which permit access to the operating head 84 in the event that manual release is desired. The solenoid 85 has a cylindrical core or armature 88 (-FIG. 1) which abuts the operating head 84 and which thrusts against the operating head for release of the locking member 42 in response to energization of the solenoid. The loaded rod 10' may be made of non-magnetic material such as a suitable grade of stainless steel to favor concentration of the magnetic flux in the armature 88.

The manner in which the described mechanism functions for its purpose may be readily understood from the foregoing description. With the device set or cocked to immobilize the rod 10 in opposition to the longitudinal load force, the various working parts are in the positions shown in FIGS. 1, 2 and 4. The longitudinal load force creates two divergent components of reaction force on each of the two latch jaws 34-, one force being axial and the other force being radial to urge the two jaws radially outward towards their released positions. The two jaws cannot retract radially outward because they back against the cam enlargements 70 of the two locking fingers 35.

The radial outward component of the reaction force that urges each of the two latch jaws 34 radially outward is resolved into two further divergent components one being radially outward to press the corresponding blocking fingers against the inner surfaces of the three rings 51-33, the other component being longitudinal or axial to tend to shift the blocking fingers longitudinally towards their release positions against the resistance of the toggle links 38, 46. Finally, the longitudinal component of reaction force acting on each blocking finger 35 is resolved by the corresponding pair of toggle links 38-40 into a major force component longitudinally of the pair of links and a minor radial inward component which is applied by the toggle links laterally to the cylindrical surface 46 of the locking member 42.

Since the final or residual component of reaction force exerted radially inwardly by the two pairs of toggle links against the cylindrical surface 46 of the locking member 42 is exceedingly small in comparison to the load imposed on the rod 10 and since this small force is applied in a direction perpendicular to the direction of release movement of the locking member, the high magnitude of the load on the rod 10 has relatively little effect with respect to resisting release operation of the locking member. Consequently the associated coil spring 44 may be a relatively weak spring that has relatively little force. For example, with a normal longitudinal load on the rod 10 on the order of 60 pounds the axial force required for release operation for the locking member 42 may be on the order of three pounds. The required release force may be even smaller if desired but the small coil spring 44 should be strong enough to prevent accidental release.

It is to be noted in FIG. 4 that the follower projection 82 of each pair of toggle links 38, 40 bears on the cylindrical surface 46 of the locking member 42 close to the brink of the inclined cam surface 50, i.e. close to the juncture between the conical cam surface and the cylindrical surface. It is also to be noted that since the follower projections 82 of the pairs of toggle links pass over the brink onto the conical cam surface 50 they are capable of camming the locking member to its release position. Thus only a slight axial retraction of the locking member 42 is required to trigger a release operation actuated by the reaction to the load force, i.e. actuated by the radially inward knee action of the toggle links in response to the load on the rod 10. In practice an axial shift of the locking member 42 by a distance of only .093 inch against the resistance of the small spring 44 may be sufficient to trigger the whole release operation. FIG. 5 shows the effect of complete retraction of the locking member 42, which retraction may be accomplished solely by manual force or may be accomplished largely by reaction force as just described.

To reset the device, i.e. to reengage the latch jaws 34 withthe rod 10, the locking member 42 is completely retracted as shown in FIG. 5 to permit the two latch jaws 34 to be held open by the two small concealed coil springs 64. The rod 10 may then be shifted longitudinally in opposition to the force of the heavy spring 14 until a selected latch shoulder 32 of the rod is positioned for engagement by the two latch jaws 34. The retraction force exerted on the locking member 42 may then be terminated to permit the latch jaws to be moved to their effective locking position by the cam operation illustrated by FIG. 6.

In FIG. 6 the released locking member 42 is urged leftward by the associated spring 44 with the consequence that the locking member acting on the follower projections 82 of the toggle links tends to cam the toggle links outward to pull on the two blocking fingers 35 with the consequence that the blocking fingers tend to cam the latch jaws 34 inward towards their positions of effective engagement with the rod 10.

A feature of the invention is that whereas the toggle links desirably minimize the component of reaction force that is applied against the periphery of the locking member 42 in the normal latching positions of the parts shown in FIG. 4, nevertheless when the rod 10 is released the toggle links cooperate with the locking member 42 to multiply the spring force created for returning the latch jaws to their effective positions. Thus in FIG. 6 where the locking member 42 is shown as under pressure by the spring 44 to cam the toggle links outward, the radial outward force that is applied to the toggle links is multiplied in the longitudinal thrust of the toggle links against the floating ring 36 for returning the blocking arms 35 to their normal positions and thereby returning the latch jaws 34 to their effective positions.

My description in specific detail of the selected embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In a mechanism for releasably holding a member against a load force exerted on the member in a given direction, the combination of:

.a shoulder on the member facing in the opposite direotion;

latch means having a latch shoulder for engagement with the shoulder on the member to oppose the load force, said latch means being retractable in a direction transverse to the direction of the load force to release the member,

at least one of said two shoulders being inclined relative to the direction of the load force for cam action between the two shoulders to create a component force to urge retraction of the latch means in reaction to the load force;

blocking means adjacent the latch means movable along a path transversely of said transverse direction between an effective position blocking retraction of the latch means and a release position freeing the latch means,

said latch means and blocking means having two mutually contacting shoulders respectively with at least one of the two last mentioned shoulders inclined relative to said transverse direction to urge retraction of the blocking member in reaction to said component force;

retaining means to releasably retain the blocking means at its effective position, said retaining means being releasable by movement in a direction laterally of said path; and

locking means manually retractable from an effective position blocking release action of the retaining means to a position releasing the retaining means.

2. A combination as set forth in claim 1 in which said retaining means comprises toggle means collapsible in said lateral direction.

3. A combination as set forth in claim 1 in which at least one of said locking means and said retaining means has a cam surface to act on the other of said locking means and said retaining means to urge the retaining means to its effective position in response to the force exerted by the spring means.

4. In a mechanism for releasably holding a member against a load force exerted on the member in a given direction, the combination of:

a shoulder on the member facing in the opposite direction;

structure adjacent the member to withstand the load force; latch means having a latch shoulder for engagement with the shoulder on the member to oppose the load force, the latch means being movably mounted on said structure for release retraction in a direction transverse to the direction of the load force, at least one of the two shoulders being inclined relative to the direction of the load force for cam action between the two shoulders to create a component force to urge retraction of the latch means in reaction to the load force; blocking means movably mounted on said structure for retraction along a path transversely of said transverse direction from an effective position blocking retraction of the latch means to a release position,

said two means having two mutually contacting shoulders respectively with at least one of the two last mentioned shoulders inclined relative to said transverse direction to urge retraction of the blocking member in reaction to said component force;

toggle linkage means extending in the general direction of said path with one end of the linkage means pivotally connected to said structure and the other end pivotally connected to said blocking means to releasably retain the block-ing means at its effective position, said linkage means being biased to collapse in a direction laterally of the path for shortening of the linkage means to permit retraction of the blocking means; and

locking means normally positioned to block collapse of the linkage means, said locking means being manually retractable to release the linkage means for collapse.

5. A combination as set forth in claim 4 which includes spring means urging the locking means towards its normal position and in which at least one of said locking means and said linkage means has a cam surface to act on the other of said locking means and said linkage means to urge the linkage means to its extended position in response to the force exerted by the spring means whereby manually releasing the locking means at its retracted position permits the spring means to urge retraction of the linkage means thereby to urge return of the blocking means to its effective position thereby to urge return of the latch means to its effective position.

6. In a mechanism for releasably holding an elongated member against a force exerted on the elongated member in a given longitudinal direction, the combination of:

shoulder means on the member facing in the opposite direction;

a structure surrounding the elongated member to withstand the load force;

a plurality of latch jaws each having a latch shoulder for engagement with the shoulder means of the elongated member to oppose the load force, said latch jaws being mounted on the fixed structure for retraction radially from effective positions engaging the shoulder means of elongated member to retracted release positions;

said shoulder means of the elongated member and the latch jaws being shaped for cam action on the latch jaws to urge the latch jaws radially outward to their released positions in reaction to the load force;

an annular member surrounding said elongated member inside said fixed structure and movable axially of the fixed structure towards and away from the plurality of latch jaws;

blocking means fixedly united with said annular member and extending therefrom longitudinally of the elongated member in the path of radial retraction of the latch jaws and normally blocking retraction of the latch jaws, said blocking means and said latch jaws having mutually contacting surfaces shaped for cam action to urge retraction of the blocking means with consequent shift of the annular member towards the latch jaws in reaction to the radially outward force of the latch jaws;

toggle linkage means pivotally connected at one end of the fixed structure in the region of the latch jaws and pivotally connected at the other end to said annular member to normally space the annular member from the latch jaws at a distance to maintain the blocking means in its effective position, said toggle linkage means being collapsible radially inwardly to permit shift of the annular member towards the latch jaws for release of the latch jaws by the blocking means, said toggle linkage means being biased to collapse in response to the longitudinal load imposed thereon by the cam action of the latch jaws against the blocking means; and

locking means radially inwardly from said toggle linkage means and normally positioned to block radially inward collapse of the toggle linkage means, said locking means being manually retractable longitudinally of the elongated member to a released position.

7. A combination as set forth in claim 6 which includes spring means urging the locking means towards its normal position and in which at least one of said locking means and said toggle linkage means is shaped for cam action on the other to urge returning of the toggle linkage means to its normal position in response to the force of the spring means whereby manually releasing the locking means at its retracted position results in the spring means urging extension of the toggle linkage means thereby urging return of the blocking means to its effective position thereby urging return of the latch jaws to their effective position.

8. In a mechanism for releasably holding a member against a load force exerted on the member in a given direction, the combination of:

latch means to engage the member to oppose the load and to retract to release the load;

locking means movable along a given path between a normal effective position to hold the latch means in engagement with the member and a retracted position to free the latch means for retraction,

said locking means having a surface substantially parallel to the given path and a non-parallel surface adjacent the parallel surface;

a series of force-dividing means acting in sequence in reaction to the load, each of the force-dividing means creating a plurality of divergent component reaction forca,

one of said force-dividing means including the latch means to divide the reaction to the load into a plurality of divergent component forces with one of the component forces urging retraction of the latch means,

the last of said force-dividing means including an element positioned to direct -a final divergent component force against said parallel surface of the locking means when the locking means is in its normal position and to direct the final component against said non-parallel surface when the locking means is retracted by a relatively small amount from its normal position,

said element and said non-parallel surface being shaped for cooperative cam action to retract the locking means in response to the final component of force whereby the cam action is triggered by retraction of the locking means through an initial minor portion of its range of release movement.

9. A combination as set forth in claim 8 which includes spring means urging the locking means towards its normal position whereby the spring means by means of said non-parallel surface and said element creates cam action to tend to advance the latching means to its position of engagement when the locking means is retracted.

10. A combination as set forth in claim 9 which includes additional weaker spring means to retract the latch means when the locking means is retracted in opposition to the first mentioned spring means.

11. In a mechanism for releasably holding a member against a load force exerted on the member in a given direction, the combination of:

latch means to engage the member to oppose the load and to retract to release the load;

locking means movable along a given path from a normal elfective position holding the latch means in engagement with the member to a retracted position to release the latct-h means; and

a series of force-dividing means acting in sequence in reaction to the load, each of the force dividing means creating a plurality of divergent component reaction forces,

one of said force-dividing means including the latch means to divide the reaction to the load into a plurality of divergent component forces with one of the component forces urging retraction of the latch means,

another of said force-dividing means including a blocking means to move from a normal position blocking retraction of the latch means to a release position freeing the latch means and to cooperate with the latch means to divide said one of the component forces into additional divergent component forces with one of the additional component forces urging the blocking means toward its release position,

the last of the pluralities of divergent forces in the series including a component of force applied to the locking means laterally of the given path.

12. A combination as set forth in claim 11 in which the last of the force dividing means in the series comprises toggle linkage means collapsible against the locking means.

13. In a mechanism for releasably holding a member against a load force exerted on the member in a given direction, the combination of:

latch means to engage the member to oppose the load and to retract to release the load;

locking means movable along a given path from a normal effective position to hold the latch means in engagement with the member to a retracted position to release the latch means,

said locking means having a longitudinal surface parallel to the given path;

a series of force-dividing means acting in sequence, each of the force-dividing means creating a plurality of divergent component forces in reaction to the load,

one of said force-dividing means including the latch means dividing the reaction to the load into a plurality of divergent component forces with one of the component forces urging retraction of the latch means,

another of said force-dividing means including a blocking means to move from a normal position blocking retraction of the latch means to a release position freeing the latch means and to cooperate with the latch means to divide said one of the component forces into additional divergent component forces with one of the additional component forces urging the blocking means towards its release position,

the last of the pluralities of divergent forces in the series including a component of force applied to the locking means perpendicular of said longitudinal surface,

said locking means having a cam surface adjacent said longitudinal surface to cause retraction movement of the locking means in response to the load when the locking means is retracted far enough for the final component to act on the cam surface.

14. A combination as set forth in claim 13 which includes spring means to urge the locking means along the given path towards its normal effective position whereby release of the locking means at its retracted position results in the application of spring force to urge the locking means towards its normal effective position with consequent action by said cam surface to tend to restore the latch means to its effective position.

15. A combination as set forth in claim 14 which includes a second relatively weak spring means to urge retraction of the latch means when the locking means is retracted in opposition to the first mentioned spring means.

16. In a mechanism for rele-asably holding an elongated member against a force exerted on the elongated member in a given longitudinal direction, the combination of:

shoulder means on the member facing in the opposite direction;

structure to withstand the load force, said structure including a cylinder surrounding the elongated member with radial clearance,

said structure forming a plurality of radial guideways inside the cylinder and a plurality of longitudinal guideways communicating with the radial guidevways respectively;

a plurality of latch jaws in the radial guideways respectively for radial retracting from effective positions engaging the shoulder means on the elongated member to retracted release positions,

said shoulder means of the elongated member and the latch jaws respectively being shaped for cam action on the latch jaws to urge the latch jaws radially outward to their release positions in reaction to the load force;

an annular member surrounding the elongated member inside the :cylinder and movable axially of the cylinder tOWIELI'dS and away from the latch jaws;

a plurality of longitudinal blocking fingers fixedly united with said annular member and extending thercfirom in the path of radial retraction of the Latch jaws and normally blocking retraction of the latch jaws, said blocking fingers and said latch jaws having mutually contacting surfaces shaped for earn action to urge retraction of the blocking fingers and thereby urge shift of the annular member towards the latch jaws in reaction to the radially outward force of the latch members;

toggle linkage means pivotally connected at one end to said structure in the region of the latch jaws and pivotally connected at the other end to said annular member to nonmally space the annular member from the latch jaws at a distance to maintain the locking fingers in their effective positions,

said toggle linkage means being collapsible radially inwardly to permit shift of the annular member towards the latch jaws for release of the latch jaws by the blocking fingers,

said toggle linkage mean-s being biased to collapse in response to the longitudinal load imposed thereon by the cam action of the latch jaws against the blocking fingers; and

annular locking means positioned radially inwardly References Cited by the Examiner UNITED STATES PATENTS 2,365,486 12/1944 Morris 64-28 2,753,969 7/1956 Chung 74584 2,844,048 7/1958 Bennett et la l. 74584 MILTON KAUFMAN, Primary Examiner.

WESLEY S. RATLIFF, JR., Examiner. 

1. IN A MECHANISM FOR RELEASABLY HOLDING A MEMBER AGAINST A LOAD FORCE EXERTED ON THE MEMBER IN A GIVEN DIRECTION, THE COMBINATION OF: A SHOULDER ON THE MEMBER FACING IN THE OPPOSITE DIRECTION; LATCH MEANS HAVING A LATCH SHOULDER FOR ENGAGEMENT WITH THE SHOULDER ON THE MEMBER OF OPPOSE THE LOAD FORCE, SAID LATCH MEANS BEING RETRACTABLE IN A DIRECTION TRANSVERSE TO THE DIRECTION OF THE LOAD FORCE TO RELEASE THE MEMBER, AT LEAST ONE OF SAID TWO SHOULDERS BEING INCLINED RELATIVE TO THE DIRECTION OF THE LOAD FORCE FOR CAM ACTION BETWEEN THE TWO DIRECTIONS TO CREATE A COMPONENT FORCE TO URGE RETRACTION OF THE LATCH MEANS IN REACTION TO THE LOAD FORCE; BLOCKING MEANS ADJACENT THE LATCH MEANS MOVABLE ALONG A PATH TRANSVERSELY OF SAID TRANSVERSE DIRECTION BETWEEN AN EFFECTIVE POSITION BLOCKING RETRACTION OF THE LATCH MEANS AND A RELEASE POSITION FREEING THE LATCH MEANS, SAID LATCH MEANS AND BLOCKING MEANS HAVING TWO MUTUALLY CONTACTING SHOULDERS RESPECTIVELY WITH AT LEAST ONE OF THE TWO LAST MENTIONED SHOULDERS INLINED RELATIVE TO SAID TRANSVERSE DIRECTION TO URGE RETRACTION OF THE BLOCKING MEMBER IN REACTION TO SAID COMPONENT FORCE; RETAINING MEANS TO RELEASABLY RETAIN THE BLOCKING MEANS AT ITS EFFECTIVE POSITION, SAID RETAINING MEANS BEING RELEASABLE BY MOVEMENT IN A DIRECTION LATERALLY OF SAID PATH; AND LOCKING MEANS MANUALLY RETRACTABLE FROM AN EFFECTIVE POSITION BLOCKING RELEASE ACTION OF THE RETAINING MEANS TO A POSITION RELEASING THE RETAINING MEANS. 